Off-Pump Coronary Artery Bypass (OPCAB) has evolved since about 1990, following the pioneering work done in North America by Ankeney in the period 1970–75, Akins et al. 1979, and Fanning et al. 1979–1992 in the U.S, and by Trapp & Bisarya in the early 1970's in Canada. In South America other pioneering was done by Benetti (1978–85) in Argentina and Buffolo (1981–85) in Brazil. Generally the anastomotic site was immobilized with stay sutures, such as the technique described by Trapp & Bisarya, who encircled the anastomotic area with sutures placed deep in the myocardium to incorporate enough muscle to suspend the heart yet prevent damage to the coronary artery. Later in the U.S. Phister (1985–90) and Gundry in 1990 (among others) performed OPCAB surgery but both had an assistant with a hand held instrument press on the surface of the heart near the anastomotic site to aid in epicardial immobilization.
In the mid 1990's various epicardial stabilizing instrument that could be attached to sternal retractors were evolved. For example U.S. Pat. No. 5,836,311 described a vacuum epicardial stabilizer, U.S. Pat. No. 5,782,746 described an adhesive coated and vacuum epicardial stabilizer, and U.S. Pat. No. 6,213,941 described a mechanical foot that pressed on the myocardium to stabilize the anastomotic site.
During the period of about five or six year following the mid 1990's OPCAB was increasingly used. Some surgeons reported that a great majority of their patients received OPCAB surgery. Initially, one driving force that brought this operative change included the potential to reduce the size of the surgical incision in the patient's chest; a second was the potential of reducing post-operative complications due to embolism or micro-embolism associated with an extracorporeal circulation and the use of the aortic cross-clamp. Perceived advantages were the potential of reducing patient post-operative pain; and the potential to shorten hospital and recovery time and hence reduce overall costs of the treatment procedure. Initially the procedure was called MIDCAB (Minimally Invasive Direct vision Coronary Artery Bypass) surgery (sometimes called “keyhole” surgery). It soon became apparent to many cardiac surgeons that a minimal incision (usually a thoracic as opposed to a sternal incision) was both surgically inadequate, and it resulted in increased post-operative pain as compared with a midline sternotomy. Hence, this procedure fell out of favor after a couple of years.
Some results of OPCAB procedures demonstrated that post-operative embolic complications were reduced, while others did not. Generally, the incidence of postoperative embolic complications did not fall as dramatically as had been expected. However with OPCAB surgery blood loss, and the volume of blood perfused during and following surgery were shown to have been significantly reduced as compared to on-pump bypass surgery. In some studies overall hospital stay and hence treatment cost did fall, although in other studies this was not found to be the case. Operating time generally increased for OPCAB procedures, and this with the high cost of disposable epicardial stabilizers largely offset the cost savings of not using a cardiopulmonary machine with its disposable blood handling circuit components.
To more easily and accurately and speedily anastomose a bypass graft on a coronary artery the immediate surface of the beating heart surrounding the anastomotic site must be rendered relatively akinetic. Stabilization of this local area may be achieved by placing a stabilizing foot (attached to the distal end of a surgical arm) on the surface of the heart to lie on either side of the anastomotic site. The proximal arm is firmly attached to a sternal retractor, thus theoretically fixing and immobilizing the stabilization foot. However, in practice prior instrument have drawbacks that this invention overcomes. For example, most disposable instruments either have a rigid (straight or curved) metal arm, or a fully articulated plastic arm. While the rigid metal arms are fairly stiff, they are not suitable for accessing the proximal obtuse marginal branches of the circumflex coronary arteries on posterior part of the epicardium or the distal circumflex arteries. By contrast, many disposable arms have plastic articulated members. Because Young's Modulus of plastic is low compared to that of stainless steel, flexure of the plastic arm by forces applied by the beating heart to the stabilizing foot causes said arm to flex significantly. Clearly, high rigidity is necessary to minimize movement under load at the anastomotic site as the heart beats. A second important consideration concerns the force that can be applied to the distal portion of the arm before one or more of the nestling articulating joints slip. Obviously the longer the arm, the greater the force moment that causes arm flexure or slippage. If all parts of the heart are to be stabilized an arm of sufficient reach and versatility is required, thus low flexure and slippage under load is advantageous. Moreover, it is highly desirable to provide to the surgeon with multiple types, configurations and sizes of stabilizing, so that the surgeon can select the optimum for individual anatomies.
The majority of the devices currently marketed for myocardial stabilization are only available as single patient use combined arm and feet, the arm and the foot being disposable. The currently marketed devices have some functional shortcomings, and do not offer a full “tool kit” to allow the surgeon to select a device configuration best suited to all surfaces of the heart. In addition, current devices do not provide sufficient adjustability to reach the entire surface of the heart. Furthermore, current devices lack the rigidity necessary to provide a stable support for remote portions of the heart. Finally, existing devices can be cumbersome to use and difficult to secure in a select orientation. The present invention is intended to overcome one or more of the problems discussed above.